package middleware

import (
	"fmt"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promauto"
)

var (
	// 请求计数器（带标签）
	httpRequestsTotal = promauto.NewCounterVec(
		prometheus.CounterOpts{
			Name: "http_requests_total",
			Help: "Total HTTP requests",
		},
		[]string{"method", "path", "status"},
	)

	httpDuration = promauto.NewHistogramVec(
		prometheus.HistogramOpts{
			Name:    "http_request_duration_seconds",
			Help:    "HTTP request latency",
			Buckets: []float64{0.1, 0.3, 0.5, 1, 3, 5},
		},
		[]string{"method", "path"},
	)
)

func PrometheusMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		if c.Request.URL.Path == "/metrics" || c.Request.URL.Path == "/healthz" {
			c.Next()
			return
		}

		start := time.Now()
		path := c.FullPath()

		if path == "" {
			path = c.Request.URL.Path
		}

		c.Next()

		duration := time.Since(start).Seconds()
		status := fmt.Sprintf("%d", c.Writer.Status())

		httpRequestsTotal.WithLabelValues(
			c.Request.Method,
			path,
			status,
		).Inc()

		httpDuration.WithLabelValues(
			c.Request.Method,
			path,
		).Observe(duration)
	}
}